Reconstructive surgery with biomaterials is commonly used to repair musculofascial defects in the abdominal wall that result from traumatic injury or ventral hernia. Current reconstructive options in this arena are autologous tissue (fascia! grafts or tissue flaps), which are limited in supply, synthetic materials such as polypropylene (PP mesh) that cause bowel adhesions, and naturally derived degradable extracellular matrix (ECM) scaffolds (AllodermZ, SurgisisZ) that are animal derived, expensive, limited in size, and provide limited control of architecture and/ or mechanical properties. The objectives of this proposal are to identify the composition, structure, and mechanical characteristics of silk fibroin and chitosan (SF-CS) scaffolds that will affect and provide spatial and temporal control of cell infiltration, collagen deposition, degradation rate, vascularization, and mechanical properties of the regenerated tissue, when implanted in an in vivo in an incisional ventral hernia repair model. We hypothesize that an increase in SF to CS ratio in SF-CS blend used to repair a defect in the abdominal wall would result in higher tensile strength of regenerated tissue characterized by directed cell infiltration and differentiation, blood vessel formation, collagen deposition, and slower degradation of SFCS blend. We will evaluate this hypothesis by investigating the following specific aims. We will repair an incisional hernia of the abdominal wall in a well established incisional ventral hernia repair guinea pig model with three SF-CS blends and compare with AllodermZ and PP mesh as positive and negative controls, respectively for both Specific Aims. Specific Aim 1. Quantify and compare the inflammatory response, vascularization, cellular infiltration, degradation of SF-CS, muscle cell differentiation, and bowel adhesions to the repair site between the three blends at 4, 7, 14, 21, 70, and 140 days in three regions of the implanted material that are overlap, junction, and center. Specific Aim 2. Evaluate and compare the ultimate tensile strength, elastic modulus, and elongation and stress at failure of SF-CS and SF-CS/musculofascial interface between three blends at the aforementioned time points. [unreadable] [unreadable] [unreadable] [unreadable]